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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

The Manned Space Platform as an evolutionary means to achieve a permanent manned orbital operations facility

An evolutionary approach to permanently manned on-orbit facilities is discussed, and it is noted that the Science and Applications Manned Space Platform, which is the first step in this evolution, can be based primarily on existing and currently planned hardware. It is shown how by upgrading the systems capabilities of the Spacelab modules, the platform can be reconfigured to provide a permanent manned research and operations facility. The facility can grow in size and capability to accommodate increases in user requirements, more experiment modules, and larger crews and to provide additional power and heat rejection. It is noted that the Growth-Permanently Manned Facility can be used for science activities and/or to support various operations functions such as space construction, servicing and maintaining space systems, and vehicle assembly.

Schwartz, J. M.↗
NASA NTRS1982

Combining analysis with optimization at Langley Research Center. An evolutionary process

The evolutionary process of combining analysis and optimization codes was traced with a view toward providing insight into the long term goal of developing the methodology for an integrated, multidisciplinary software system for the concurrent analysis and optimization of aerospace structures. It was traced along the lines of strength sizing, concurrent strength and flutter sizing, and general optimization to define a near-term goal for combining analysis and optimization codes. Development of a modular software system combining general-purpose, state-of-the-art, production-level analysis computer programs for structures, aerodynamics, and aeroelasticity with a state-of-the-art optimization program is required. Incorporation of a modular and flexible structural optimization software system into a state-of-the-art finite element analysis computer program will facilitate this effort. This effort results in the software system used that is controlled with a special-purpose language, communicates with a data management system, and is easily modified for adding new programs and capabilities. A 337 degree-of-freedom finite element model is used in verifying the accuracy of this system.

Rogers, J. L., Jr.↗
NASA NTRS1982

Evolutionary space platform concept study. Volume 2, part A: SASP special emphasis trade studies

Efforts are in progress to define an approach to provide a simple and cost effective solution to the problem of long duration space flight. This approach involves a Space Platform in low Earth orbit, which can be tended by the Space Shuttle and which will provide, for extended periods of time, stability, utilities and access for a variety of replaceable payloads. The feasibility of an evolutionary space system which would cost effectively support unmanned payloads in groups, using a Space Platform which provides centralized basic subsystems is addressed.

Source record↗
NASA NTRS1983

Productivity in an evolutionary space station

Space station productivity is treated from a systems point of view, considering the functions and attributes of space station development, formation, and operation that affect productivity. An optimum planning method is needed to assure that the station will have mission flexibility, technology advancement, maintainability, and evolutionary capability. Advanced technology will be designed into the housekeeping and utility functions of the station. Greater risk taking may be allowed into designs if the potential benefits of the advanced system support the risk, and if the system can be buffered from causing a failure cascade throughout the station. A common data base is needed to store and track all designs, developments, and changes in the station subsystems. Systems that can be automated and free the human inhabitants for more productive work are favored, as are modular components that are highly fault-free. Human control must also be possible, especially during check-out and verification, and also for teaching the automated systems new or modified tasks.

Anderson, J. L.↗
NASA NTRS1983

On the evolutionary constraint surface of hydra

Food consumption, body size, and budding rate were measured simultaneously in isolated individual hydra of six strains. For each individual hydra the three measurements define a point in the three dimensional space with axes: food consumption, budding rate, and body size. These points lie on a single surface, regardless of species. Floating rate and incidence of sexuality map onto this surface. It is suggested that this surface is an example of a general class of evolutionary constraint surfaces derived from the conjunction of evolutinary theory and the theory of ecological resource budgets. These constraint surfaces correspond to microevolutionary domains.

Slobodkin, L. B.↗
NASA NTRS1983

Evolutionary connections of biological kingdoms based on protein and nucleic acid sequence evidence

Prokaryotic and eukaryotic evolutionary trees are developed from protein and nucleic-acid sequences by the methods of numerical taxonomy. Trees are presented for bacterial ferredoxins, 5S ribosomal RNA, c-type cytochromes , cytochromes c2 and c', and 5.8S ribosomal RNA; the implications for early evolution are discussed; and a composite tree showing the branching of the anaerobes, aerobes, archaebacteria, and eukaryotes is shown. Single lines are found for all oxygen-evolving photosynthetic forms and for the salt-loving and high-temperature forms of archaebacteria. It is argued that the eukaryote mitochondria, chloroplasts, and cytoplasmic host material are descended from free-living prokaryotes that formed symbiotic associations, with more than one symbiotic event involved in the evolution of each organelle.

Dayhoff, M. O.↗
NASA NTRS1984

Evolutionary history of CI and CM chondrites

It is now clear that several different processes have acted upon various components of carbonaceous chondrites, and that at least some of those processes occurred very early in solar system history. Because these meteorites are breccias, petrographic relationships are seldom informative about the order in which those processes took place. Nonetheless, information about such an evolutionary sequence would be of potential value in defining the nature of the source region for these meteorites. Implantation of solar wind derived noble gases into CI magnetite apparently postdated the period of aqueous activity believed to be responsible for magnetite production. Carbonate crystallization roughly coincided with one or more episodes of impact driven brecciation.

Kerridge, J. F.↗
NASA NTRS1985

Discovery of oxygen in the PG 1159 degenerate stars - A direct evolutionary link to O VI planetary nebula nuclei and confirmation of pulsation theory

The discovery of strong O VI absorption/emission lines in five members of the PG 1159 degenerate stars is reported. It is shown that the optical spectra are dominated by C IV, O VI, and He II, with no detectable N lines. It is confirmed that the planetary nebula-central star, K1-16, which is found to be a pulsating star by Grauer and Bond (1984), is a member of the spectroscopic group. The detection of strong oxygen features in the photospheres of the objects provides support of the prediction of Starrfield et al. (1984). The properties of the PG 1159 stars are compared with the so-called O VI central stars of planetary nebulae and both groups of stars are found to have similar spectral features, temperatures, and luminosities. The implications of the O VI/PG 1159 evolutionary link are assessed.

Sion, E. M.↗
NASA NTRS1987

Synthetic filter photometry and evolutionary status of two Be stars in the association Per OB1

Stromgren and H-beta colors have been determined from spectrophotometric observations for two Be stars without published photometry in the association Per OB1: HD 12856 (B0 pe) and HD 13890 (B1 III:pe). Stellar parameters and improved spectral types are then derived from the color indices using the calibrations of Jakobsen (1986), and independently from the BCD classification method. The intrinsic properties of HD 12856 and HD 13890 are compared with those of normal B stars and are used to estimate their evolutionary status.

Torres, Ana V.↗
NASA NTRS1986

Evolution of substellar 'brown' dwarfs and the evolutionary status of VB8B

Detailed evolutionary calculations for stars near and below the minimum main sequence (MS) mass are presented, and the results are compared to VB8B. The standard set of stellar equations are solved, and the influence of both high and low grain opacities is assessed. All masses less than 0.08 solar are found to evolve to 0.0001 solar luminosities in a billion years or less. Both 0.08 solar mass and 0.075 solar mass stars become MS stars after five billion years, but with luminosities substantially below 0.0001 solar. The best fit to VB8B is 0.06 + or - 0.02 solar mass, but less than 0.8 solar mass. Depending upon its very precise mass, VB8B can be either a substellar brown dwarf with an age of 0.3-3 billion years, or an MS star with an age anywhere from two billion years to a Hubble time.

Stringfellow, Guy S.↗
NASA NTRS1987

Evolutionary sequences for horizontal branch stars

A new grid of canonical evolutionary horizontal branch (HB) sequences is presented. Sequences are computed for each combination of the following helium and heavy-element abundances, respectively: Y(main sequence) = 0.20, 0.25, 0.30, and Z = 0.0001, 0.001, and 0.01. The results show that the bifurcation point at which the HB morphology changes from redward-evolving tracks to tracks with blueward loops shifts to higher effective temperatures with increasing helium abundance or metallicity. The sequences can be used to study in more detail how a number of HB properties such as the HB lifetime, the effective temperature at the bifurcation point in the track morphology, the luminosity dropoff of the blue HB, and the luminosity width of the red HB depend on the composition.

Sweigart, Allen V.↗
NASA NTRS1987

Evolutionary helium and CNO anomalies in the atmospheres and winds of massive hot stars

The ubiquitous evidence for processed materials in the atmospheres, winds, and circumstellar ejecta of massive stars is reviewed. A broad array of normal and peculiar evolutionary stages is considered, up to and including Type II supernova progenitors. The quantitative analysis of these spectra is difficult, and until recently for the most part only qualitative or approximate results have been available. However, several important current programs promise reliable abundance calculations. A significant emerging result is that the morphologically normal majority of both hot and cold supergiants may already display an admixture of CNO-cycle products in their atmospheres. It may become possible in this way to identify blue supergiants returning from the red supergiant region, as appears to have been the case for the SN 1987A progenitor.

Walborn, Nolan R.↗
NASA NTRS1987

The evolutionary status of 4U 1820-30

The evolution of an ultracompact binary wherein mass transfer is driven by the emission of gravitational radiation is calculated, emphasizing the systematic study of how the rate of change in orbital period depends on the various system parameters. Analytic scaling laws are derived describing how the mass of the secondary, the mass transfer rate, and the rate of change of period depend on the binary system parameters, and these simple relations are applied to the 4U 1820-30 system. Detailed numerical evolutionary calculations are performed utilizing Zapolsky-Salpeter (1969) models for cold stars, but allowing for the possibility that the secondary has not yet reached a completely degenerate configuration. The results are used to set significant constraints on the deviation from a completely degenerate configuration of the secondary, the systemic mass-loss parameters, and the mass of the neutron star in the 4U 1820-30 system.

Rappaport, S.↗
NASA NTRS1987

Evolutionary tracks of the terrestrial planets

On the basis of the model proposed by Matsui and Abe (1986) it is shown that two major factors - distance from the sun and the efficiency of retention of accretional energy - control the early evolution of the terrestrial planets. A diagram of accretional energy versus the optical depth of a protoatmosphere provides a means to follow the evolutionary track of surface temperature of the terrestrial planets and an explanation for why the third planet in our solar system is an 'aqua' planet.

Matsui, Takafumi↗
NASA NTRS1987

Intelligent systems and robotics for an evolutionary Space Station

The Space Station will be a multipurpose space facility to acquire and exploit unique knowledge with a planned lifetime of greater than 20 years. It will include laboratories for science and manufacturing, provide a platform for earth and interplanetary observations, conduct satellite servicing, and serve as a transportation node for potential manned geosynchronous, lunar, and Mars missions. Environmental safety considerations and limited manpower resources require the extensive use of intelligent systems and flexible robotics on the Space Station. Design accommodations must be planned in advance to allow incorporation of these advancing technologies on the evolutionary Space Station.

Erickson, Jon D.↗
NASA NTRS1989

The development of the red giant branch. I - Theoretical evolutionary sequences

A grid of 100 evolutionary sequences extending from the zero-age main sequence to the onset of helium burning has been computed for stellar masses between 1.4 and 3.4 solar masses, helium abundances of 0.20 and 0.30, and heavy-element abundances of 0.004, 0.01, and 0.04. Using these computations the transition in the morphology of the red giant branch (RGB) between low-mass stars, which have an extended and luminous first RGB phase prior to helium ignition, and intermediate-mass stars, which do not, is investigated. Extensive tabulations of the numerical results are provided to aid in applying these sequences. The effects of the first dredge-up on the surface helium and CNO abundances of the sequences is discussed.

Sweigart, Allen V.↗
NASA NTRS1991

The Langley Research Center CSI phase-0 evolutionary model testbed-design and experimental results

A testbed for the development of Controls Structures Interaction (CSI) technology is described. The design philosophy, capabilities, and early experimental results are presented to introduce some of the ongoing CSI research at NASA-Langley. The testbed, referred to as the Phase 0 version of the CSI Evolutionary model (CEM), is the first stage of model complexity designed to show the benefits of CSI technology and to identify weaknesses in current capabilities. Early closed loop test results have shown non-model based controllers can provide an order of magnitude increase in damping in the first few flexible vibration modes. Model based controllers for higher performance will need to be robust to model uncertainty as verified by System ID tests. Data are presented that show finite element model predictions of frequency differ from those obtained from tests. Plans are also presented for evolution of the CEM to study integrated controller and structure design as well as multiple payload dynamics.

Belvin, W. K.↗
NASA NTRS1990

Evolutionary use of nuclear electric propulsion

Evolving new propulsion technologies through a rational and conscious effort to minimize development costs and program risks while maximizing the performance benefits is intuitively practical. A phased approach to the evolution of nuclear electric propulsion from use on planetary probes, to lunar cargo vehicles, and finally to manned Mars missions with a concomitant growth in technology is considered. Technology levels and system component makeup are discussed for nuclear power systems and both ion and magnetoplasmadynamic thrusters. Mission scenarios are described, which include analysis of a probe to Pluto, a lunar cargo mission, Martian split, all-up, and quick-trip mission options. Evolutionary progression of the use of NEP in such missions is discussed.

Hack, K. J.↗